Set Up A Loose-Footed Mainsail

Set Up A Loose-Footed Mainsail

Back in the 1970’s, the IOR (International Offshore Rule) for racing was all the rage.  One interesting part of the rule was a heavy penalty for loose-footed mainsails.  That is, not having a bolt rope on the foot of the mainsail which was fed into a slot on the top of the boom.  The rule-makers knew that more efficient sail shapes could be achieved with a loose-footed mainsail and an adjustable clew outhaul.  The mainsail’s shape could be more easily optimized for light, moderate, and strong winds - - - as well as for upwind close hauled sailing, for reaching, and for running.

During those years, many of the manufacturers “went along with” the IOR rule and produced boats with a “boom-footed” mainsail…  even on small sailboats where loose-footed was much easier to rig and sail. 

A loose-footed set up has the tack corner of the mainsail secured to the boom near the gooseneck at the forward end of the boom.  And, only has a clew corner car that slips into the slot on the top of the boom.  The clew’s car can be easily moved forward or aft along the slot by means of an adjustment line.  Moving the car forward creates more draft in the mainsail and more power.  Moving the care forward for reaching and running really works well.  Likewise, moving the car forward for light breezes often develops more lift on most boats.

Moving the car aft flattens the mainsail; allowing the boat to point higher without sacrificing much speed.  Moving the car aft as the wind increases also works well since the sail becomes less powerful as it is flattened.

On Snickerdoodle, I have the control lines all led aft on the cabin top so that it is really easy to change settings.  The adjustable clew outhaul control line is secured to the clew corner of the sail; and is then led through a block and forward to the forward end of the boom.  A cheek-block on the side of the boom redirects the adjustment line to a swivel block and clam cleat mounted near the base of the mast.  The adjustment line is long enough to reach the back of the cabin top where I can easily get to it.

If you are out at the Bitter End Marina at Bayview Idaho and want to see the whole lash-up, stop by and say hi.